1. Field of the Invention
This invention generally relates to a technique for removing micro-debris, and more specifically, to a method for removing micro-debris generated in laser machining processes performed on machined objects and device of the same.
2. Description of Related Art
Along with the development in semiconductor and microsystem technologies, developments of various electronic products are toward higher memory capacities and higher performances; therefore requirements of component parts of electronic products are toward higher precision and miniaturization. Prior semiconductor fabrication technique is integrated with photolithography and etching technologies for producing fine line structures and patterns; and since laser machining is capable of performing micro drilling, micro cutting, micro carving, micro machining, micro soldering, etc., laser machining has been commonly used to replace some of conventional semiconductor fabrication technologies.
Accordingly, one feature of laser machining is providing excellent laser beam parallelism, theoretically, particle diameter thereof can be bunched together to under 1 μm, and temperature can reach above 10000° C., and it is capable of performing very microscopic melting and vaporization machining processes without affecting mechanical and thermomagnetic properties of nearby materials. However, in a process of laser micromachining performed on machined object, ablated micro-debris will scatter all over the surroundings of the machined object, and the micro-debris will even accumulate on the machined object if not removed instantly, subsequently decreasing machining precision and increase surface roughness.
According to established micro-debris removal technologies, air flow is mostly adopted to eliminate micro-debris, such as air blowing, air suction, and a combination of both, etc.. An example of related technology is disclosed by U.S. Pat. No. 6,797,919.
According to the U.S. Pat. No. 6,797,919, a laser ablation nozzle assembly is disclosed; said patent is characterized by disposing a laser channel for vacuum removing micro-debris, the laser channel comprises internal threads and is targeting directly at the machined object. Such internal threads enable air flow entering the laser channel via the vacuum channel to cause a turbulent flow effect for removing micro-debris generated during the machining process. In addition, said technology can further dispose an air pressure channel inside the nozzle for forming an air flow circuit, thereby preventing the micro-debris from attaching onto the laser channel above the machined object and affecting proper laser performance.
However, when using air flow to remove micro-debris, air blowing nozzle or air suction nozzle should be disposed properly and also air flow direction has to be well controlled, but the air blowing nozzle or air suction nozzle cannot be adjusted easily since it is disposed closely to the laser beam, thereby causing micro-debris to be removed incompletely or flow to improper location. Meanwhile, temperature is one of important parameters in laser machining, while removing micro-debris by means of air blowing, air suction, or both, turbulent flow will cause uneven temperature in neighboring areas of the machining location, and when the temperature or temperature difference is too high, precision and quality of laser machining are decreased, or even worse, the process of micro-debris ablation cannot be performed normally.
In addition, said patent technology has to be disposed with air pressure source or negative pressure source for correspondingly supporting the air blowing nozzle or air gushing nozzle to remove micro-debris, which not only increases cost, but also occupies more space and causes more inconvenience during use. Besides, said patent technology has to be operated in a vacuum environment, equipments necessary to implement this are usually very expensive.
Furthermore, said patent technology involves a machining method using laser beam to operate on machined object. Therefore, a machining platform carrying the machined object is moved to facilitate machining range. However, when laser direct writing technique is applied to perform a machining process, in order to adjust the machining range, the focus of the laser beam is constantly adjusted through optical component such as a lens. As a result, if said patent technology is applied, location of the air blowing nozzle or air gushing nozzle should be changed correspondingly as well, thereby causing difficulty in removing micro-debris; in other words, said patent technology is not applicable to the laser direct writing technique.
In addition, an acoustic levitation and methods for manipulating levitated objects are disclosed according to U.S. Pat. No. 4,284,403, said patent technology uses acoustic levitation to manipulate levitated objects; said patent is characterized by disposing a vibrator and an amplifier below levitated objects capable of generating acoustic waves, and also disposing an acoustic wave reflector above the levitated objects, consequently, acoustic waves generated by the source will be reflected by the acoustic wave reflector. Interference between the sound waves and the reflected waves will further generate standing waves and standing wave nodes. Acoustic levitation occurs at these standing wave nodes, thereby enabling levitated objects to float at the standing wave nodes. In addition, according to said patent technology, the acoustic wave reflector is connected to a movable platform, by moving the acoustic wave reflector, the standing waves and standing wave nodes are also moved, therefore, the levitated objects are also moved.
However, said patent technology does not discuss how to remove micro-debris produced in a laser machining process. A supplementary technique of standing waves and standing wave nodes is disclosed according to U.S. Pat. Nos. 4,284,403. 7,200,493 discloses a technology, wherein molecules are concentrated at standing wave nodes and then sieved. Likewise, U.S. Pat. No. 4,284,403 is applicable to no-container high purity filtering technology for glass optical fiber, while U.S. Pat. No. 7,200,493 is applicable to technology for sieving crystalline state or non-crystalline state of molecules, neither mentions how to remove micro-debris generated in a laser machining process. Therefore, even similar principles are applied, there is no mention of removal of micro-debris during laser machining
Hence, it is a highly urgent issue in the industry to provide a method for removing micro-debris produced in laser machining processes and device of the same capable of effectively solving abovementioned drawbacks of the prior art.